This invention generally relates to electronic systems and in particular it relates to differential receivers.
The input stage of a prior art small swing differential receiver has been implemented as shown in FIG. 1. The differential receiver of FIG. 1 contains three P-channel transistors 20, 22, and 24, and four N-channel transistors 26, 28, 30, and 32. Another circuit supplies the bias voltage to the gate of transistor 20. Then transistor 20 acts as a current source which is tied to a differential pair formed by transistors 22 and 24. When input node 34 is lower in voltage than input node 36, a majority of the current supplied by transistor 20 is steered through transistor 22, with the remainder of this current flowing through transistor 24. In order to insure that a large enough signal swing is generated at output nodes 38 and 40, cross-coupled transistors 26 and 28 are added, which gives this circuit additional gain. However, adding transistors 26 and 28 can cause the signal swing to become too large under some conditions, so clamp transistors 30 and 32 are added.
Generally, and in one form of the invention, the differential receiver circuit includes: a current source; a differential pair coupled to the current source; a first transistor coupled to a first branch of the differential pair; a second transistor coupled to a second branch of the differential pair, the first and second transistors are cross coupled; a third transistor coupled in series with the first transistor; a fourth transistor coupled in series with the second transistor; a fifth transistor coupled in parallel with the first and third transistors; and a sixth transistor coupled in parallel with the second and fourth transistors.